The AOD is like any other automatic transmission. When your speed gets low enough, it downshifts to a lower gear. There should be no lugging in third gear.

The AOD has a selection just off of Full drive that locks out the 4th gear. This is designed to be used in slower in-town traffic where you barely get the car going fast enough for 4th to engage. The lockout keeps the trans out of 4th so it doesn't put extra wear and tear constantly going in and out of 4th gear. Other than that, all the driving features work the same.

 

The lockup vs. non-lock up has nothing to do with 4th gear. With a non-lockup converter it will still go into 4th (overdrive) but the converter stays unlocked for more multiplication. Leaving the shifter in 3rd will prevent over-drive engagement and some lugging/bucking, but you won't get the gas mileage of OD. Anything over 40mph and I use OD.

I have a Lentech AOD with non-lockup and while it is a lot of fun and gets the rpm into the torque band of the engine quickly, a non-lock up converter will KILL gas mileage (if it concerns you). It's actually almost like having a slipping transmission...

A lot depends upon power level too. If the engine is only making 300hp (or less) I'd stick with the lock-up converter anyway, and save some gas mileage. Lentech told me I could gain back as much as 4mpg converting to a lock-up, but I don't want to yank the trans right now (long tube headers)...

 

I am convinced you are confusing OD and locking converters functionality based on your recent series of posts. They are 2 completely separate items.

A good rule is, if you are planning a performance motor (and 400 HP would count) than you don't want a stock locking converter. You need a more performance AOD.

You want a non-locking converter so you can run a single input shaft. You can upgrade the hard parts if you want to the same as the 4r70w internals for a beefier build, you add the extra clutches and then put a good valve body in.

Standard AOD shift pattern is:

D on the shifter - 1, 2, 3 and OD
2 on the shifter - 1, 2 and 3rd gears
1 first gear

If you put the Lentech valve body in with the switch for OD then the shift selector with funtion:
D: 1, 2 and 3
2: 1 and 2
1: 1
And the OD is controlled by the Switch.


A locking converter is designed to improve efficiency while driving. When cruising it disconnects the fluid coupling a TC normally provide between the motor and trans and simply 'locks up' creating a direct coupling between the motor and the trans. This works to further reduce cruising RPMs over a standard overdrive without a locking converter but also means you can get a slight lag when you need to downshift and accelerate quickly as you wait for it to unlock. In higher HPO applications the 2 piece shaft which is designed to allow the converter to lock up snaps when power is applied to it quickly which is why the first performance upgrade to any AOD really is to ditch the lockup converter setup.

 

I got it!
Thanks guys.... I'll probably go with the standard AOD with lock-up for now. I don't see myself going for the 400 hp motor for a few years yet. When I do, I'll probably go with the non-locking Lenntech Street Bruiser, but right now with the torque converter it's over $3000 NOT including mounting bracket or installation. I can get into a good rebuilt AOD with installation for under $2000. That's including the trans mount,trans cooler, flexplate, dipstick.....with a great warranty yet.
If I go to that stroker motor then someone here will get a great deal on a freshly rebuilt AOD with the right upgrades.

 

Hmm... I can't believe that no one mentioned this...

If you read the owner's manual for an AOD, it states that you should NOT operate the AOD in drive for extended periods of wide open throttle (WOT) operation. This is not due to the frailty of the two piece input shaft, but rather for the load on the overdrive bands, which are another relatively weak point on the transmission.

As stated above, for stock to mild engine builds and primarily street use lock up converters are preferred. Just don't go flooring it on a track (not the street!) for long periods of time in the drive position.

For high power engines internal upgrades are recommended, such as wider bands, mechanical diodes, hardened input shafts, etc. But you can still run a lock up converter with a pretty powerful engine with the right components.

Personally, I think the non lockup converters are best suited for racing applications. By the time you reach this level, you should probably be considering the more modern and stronger electronic versions of this transmission such as the 4R70W.

Good luck,
-Rory